[FIXED] Indexing correctly within a for-loop and while-loop

Issue

I have a set of brand numbers for a webpage url. I convert the webpage url into an f-string, and apply the brand number where it's supposed to. Each page has a unique ID to load the next page. I'm trying to extract this next page whilst matching the brand number the Id belongs to.

Here's some sample code:

import requests
import pandas as pd
from bs4 import BeautifulSoup

brands = [989,1344,474,1237,886,1,328,2188]

testid = {}
for b in brands:
    url = f'https://webapi.depop.com/api/v2/search/products/?brands={b}&itemsPerPage=24&country=gb&currency=GBP&sort=relevance'
    payload={}
    headers = {}
    response = requests.request("GET", url, headers=headers, data=payload)
    test= pd.read_json(StringIO(response.text), lines=True)
    for m in test['meta'].items():
        if m[1]['hasMore'] == True:
            testid[str(b)]= [m[1]['cursor']]
        else:
            continue
    for br in testid.keys():
        while True:
            html = f'https://webapi.depop.com/api/v2/search/products/?brands={br}&cursor={testid[str(br)][-1]}&itemsPerPage=24&country=gb&currency=GBP&sort=relevance'
            r = requests.request("GET",html, headers=headers, data=payload)
            read_id = pd.read_json(StringIO(r.text), lines=True)
            for m in read_id['meta'].items():
                try:
                    testid[str(br)].append(m[1]['cursor'])
                except:
                    continue

Here's the output it produces:

{'989': ['MnwyNHwxNjQwMDMwODcw']}

However, it replaces the values originally in the brand number and only leaves the last one collected. It should leave a list and produce something like this:

{'989': ['MnwyNHwxNjQwMDI4Mzk1', ...],
 '1344': ['MnwyNHwxNjQwMDI4Mzk2', ...],
 '474': ['MnwyNHwxNjQwMDI4Mzk3', ...],
 '1237': ['MnwyNHwxNjQwMDI4Mzk3', ...],
 '886': ['MnwyNHwxNjQwMDI4Mzk4', ...],
 '1': ['MnwyNHwxNjQwMDI4Mzk4', ...],
 '328': ['MnwyNHwxNjQwMDI4Mzk5', ...],

Where the triple dots ... denotes the additional ID values collected from the page with that brand number. How can I get an output like this?

Solution

After setting the testid list to be a collections.defaultdict(list) the rest falls out in a rather straightforward manner..

Note: I'm only going to fetch the first 3 cursors of any product but you can do them all as you like.

import collections
import requests

brands = [989,1344,474,1237,886,1,328,2188]
testid = collections.defaultdict(list)
for b in brands:
    headers = {}
    payload={}
    url = f"https://webapi.depop.com/api/v2/search/products/?brands={b}&itemsPerPage=24&country=gb&currency=GBP&sort=relevance"

    response = requests.request("GET", url, headers=headers, data=payload)
    data = response.json()
    i = 0 # short circuit 

    while data.get("meta", {}).get("hasMore") and i < 3:
        cursor = data.get("meta", {}).get("cursor")
        testid[str(b)].append(cursor)
        response = requests.request("GET", f"{url}&cursor={cursor}", headers=headers, data=payload)
        data = response.json()
        i += 1

for key, value in testid.items():
    print(key, value)

This gives us:

989  ['MnwyNHwxNjQwMDMzMjM0']
1344 ['MnwyNHwxNjQwMDMzMjM1', 'M3w0OHwxNjQwMDMzMjM1', 'NHw3MnwxNjQwMDMzMjM1']
474  ['MnwyNHwxNjQwMDMzMjM3', 'M3w0OHwxNjQwMDMzMjM3', 'NHw3MnwxNjQwMDMzMjM3']
1237 ['MnwyNHwxNjQwMDMzMjM5', 'M3w0OHwxNjQwMDMzMjM5', 'NHw3MnwxNjQwMDMzMjM5']
886  ['MnwyNHwxNjQwMDMzMjQz', 'M3w0OHwxNjQwMDMzMjQz', 'NHw3MnwxNjQwMDMzMjQz']
1    ['MnwyNHwxNjQwMDMzMjQ4', 'M3w0OHwxNjQwMDMzMjQ4', 'NHw3MnwxNjQwMDMzMjQ4']
328  ['MnwyNHwxNjQwMDMzMjUz', 'M3w0OHwxNjQwMDMzMjUz', 'NHw3MnwxNjQwMDMzMjUz']

Wait a sec.... What is going on with:

data.get("meta", {}).get("hasMore")

Great question and I should have explained it before.

So, there is a chance that data.meta is not defined and if that was true, the following would fail;

data["meta"].get("hasMore")

as would

data.get("meta").get("hasMore")

So what we did:

data.get("meta", {}).get("hasMore")

was use the second parameter of get() to provide a default value. In this case it is just an empty dict but that is enough for us to safely chain the followup .get("hasMore") onto.

Answered By - JonSG